Study on the Spatial Distribution Patterns of Tomato Mosaic Disease and Its Aphid Vectors

Based on the results of field investigation in spring and autumn tomato planted fields in Guangdong province in 1998, a detail analysis was conducted for spatial distributions of the diseased plants and its aphid vectors (Myzus persicae ) in autumn with several indices of spatial pattern. Spatial distribution analysis of the disease showed that the distribution patterns of diseased plants in the field were changed with the time passing. At the beginning of the disease developping, a random pattern was observed, then a clustering type of distribution, and an even pattern at the last stage of the plant. Further analysis of the aphid vectors in autumn crop showed that the alatae always had a clustering type of distribution. It was showed in the present study that the distribution of alatae was similar to that of the diseased plants, and suggested that the alatae were the main effective vectors of the disease.